Twilight and Sunset spent their last night in the Mirror World at Twilight’s parents’ house. The day was full of stress-free fun, friends, and family. Soon, they’ll begin their move across dimensions and settle down in Canterlot for the next few months.
Or that could just be her leg. Hard to tell
Still though, I'm with the in-universe characters in that I can't find a scientifically plausible way in which this could have happened